She is a real woman: her breasts are heavy and her hips wide. She sits asleep in the morning sun, fitfully dreaming of the child (a tiny wooden figure) that has been stolen from her. Indeed, Yerma is all woman, but she lacks the one thing that would make her happy: a baby. She has been married seven years, but time ebbs and flows like the mountain stream where the village women wash their clothes and she is no longer young. Around her, women and animals bloom, trees and flowers blossom, and her womb fills up with stones.

The early 20th-century playwright Federico Garcia Lorca wrote like a woman might have written of her secret thoughts and feelings. Pam Gems's magnificent adaptation of this poetic tragedy is a gift: soft, yet as hard as the sun-baked soil. When Maria is trying to explain to Yerma what it feels like to be pregnant, she says: "Have you ever held a live bird in your hand? It's like that, but in your blood."

It is that sense of being in touch, umbilically connected to the earthy, rural world, that marks this sensitive evening, a mood that on opening night could not be broken even by evacuation of the theatre due to a fire alert in a neighbouring shop. When the play resumed, we were instantly transported back to rural early 20th-century Spain. A lot of that is down to Akintayo Akinbode's atmospheric music, mixing the Catholic and the pagan, folk songs and something stranger and more exotic.

Helena Kaut-Howson's production is beautiful, too, a finely judged mixture of repressed emotion and welling grief. It builds to its tragic climax with an ease that makes the unthinkable seem totally reasonable to a 21st-century urban audience.

There is an excellent cast of women, who play lusty wives or dried-up crones, and great support from Peter Gowen as Yerma's uptight husband and Oliver Haden as the man she should have married. But the evening is carried by Denise Black as Yerma, whose swelling with longing and shrivelling with despair is like witnessing some terrible phantom pregnancy.